Abstract
Ercolania boodleae (BABA) occurred throughout the year, being especially abundant from winter to early summer, on the coasts of Sado Island. The animal tended to congregate on a green alga Chaetomorpha aerea. The population of the animal settling on this alga consisted of much larger individuals than those which had been confined within the predominatly Ulva, Enteromorpha or Cladophora isolated localities. Under laboratory conditions, the animal was affected considerably by the alga supplied. The efficiency of animal nutrition, which was determined on the basis of the size increase, reproductive activity and viability, was found to decrease in the following order : Ch. aerea>Ch. moniligera>Cl. densa>Cl. rudolphiana≧the algae belonging to the Ulvaceae and Bryopsidaceae. In selecting food the animal's tactile sense of the physico-chemical properties of the algae may play an important role. In addition to this it was also considered that the distribution of the animal is changed occasionally by wave action, and that the animal may produce three or more generations in a year.
